Slime control compositions and their use

ABSTRACT

THE PRESENT INVENTION RELATES TO CERTAIN PROCESSES AND COMPOSITIONS USEFUL FOR INHIBITING THE GROWTH OF SLIME IN WATER AND, IN PARTICULAR, WATER USED FOR INDUSTRIAL PURPOSES; FOR EXAMPLE, IN THE MANUFACTURE OF PULP PAPER, IN THE MANUFACTURE OF PAPER, IN COOLING WATER SYSTEMS AND IN EFFLUENT WATER TREATMENT. THE NOVEL PROCESSES AND COMPOSITIONS OF THE PRESENT INVENTION ARE PROCESSES OR MIXTURES WHICH SHOW UNEXPECTED SYNERGISTIC ACTIVITY AGAINST MICROORGANISMS, INCLUDING BACTERIA, FUNGI AND ALGAE, WHICH PRODUCE SLIME IN AQUEOUS SYSTEMS OR BODIES WHICH ARE OBJECTIONABLE FROM EITHER AN OPERATIONAL OR AESTHERIC POINT OF VIEW. SPECIFICALLY, THE INVENTION IS DIRECTED TO THE USE OF COMPOSITIONS COMPRISING A COMBINATION OF A BROMONITROSTYRENE AND A SPECIFIC QUATERNARY N-ALKYL AMMONIUM CHLORIDE DETERGENT HAVING AN ALKYL DISTRIBUTION OF FROM ABOUT 12 TO 18.

US. Cl. 71-67 12 Claims ABSTRACT OF THE DISCLOSURE The present inventionrelates to certain processes and compositions useful for inhibiting thegrowth of slime in water and, in particular, water used for industrialpurposes; for example, in the manufacture of pulp paper, in themanufacture of paper, in cooling water systems and in effluent watertreatment. The novel processes and compositions of the present inventionare processes or mixtures which show unexpected synergistic activityagainst microorganisms, including bacteria, fungi and algae, whichproduce slime in aqueous systems'or bodies which are objectionable fromeither an operational or aesthetic point of View. Specifically, theinvention is directed to the use of compositions comprising acombination of a bromonitrostyrene and a specific quaternary N-alkylammonium chloride detergent having an alkyl distribution of from about12 to 18.

This application is a continuation-in-part of application Ser. No. 464,filed Jan. 2, 1970, now abandoned.

BACKGROUND OF THE INVENTION The formation of slime by microorganisms isa problem which attends many systems. For example, lagoons, lakes,ponds, pools and such systems as cooling water systems and pulp andpaper mill systems all possess conditions which are conducive to thegrowth and reproduction of slime-forming microorganisms. In bothonce-through and recirculating cooling systems, for example, whichemploy large quantities of water as a cooling medium, the formation ofslime by microorganisms is an extensive and constant problem.

Airborne organisms are readily entrained in the water from coolingtowers and find this warm medium an ideal enviroment for growth andmultiplication. Aerobic and heliotropic organisms flourish on the towerproper while other organisms colonize and grow in such areas as thetower sump and the piping and passages of the cooling system. Such slimeserves to deteriorate the tower structure in the case of wooden towers.In addition, the deposition of slime on metal surfaces promotescorrosion. Furthermore, slime carried through the cooling system plugsand fouls lines, valves, strainers, etc. and deposits on heat exchangesurfaces. In the latter case, the impedance of heat transfer can greatlyreduce the efficiency of the cooling system.

In pulp and paper mill systems, slime formed by microorganisms is alsofrequently and, in fact, commonly encountered. Fouling or plugging byslime also occurs in the case of pulp and paper mill systems. Of greatersignificance, the slime becomes entrained in the paper produced to causebreakouts on the paper machines with consequent work stoppages and theloss of production time or unsightly blemishes'in the final productwhich results in rejects and wasted output. The previously discussedproblems have resulted in the extensive utilization of biocides incooling Water and pulp and paper mill systems. Materials which haveenjoyed widespread use in such applicanited Sttes Patent ice tionsinclude chlorine, organo-mercurials, chlorinated phenols,organo-bromines, and various organo-sulfur compounds. All of thesecompounds are generally useful for this purpose but each is attended bya variety of impediments. For example, chlorination is limited both byits specific toxicity for slime-forming organisms at economic levels andby the ability of chlorine to react which results in the expenditure ofthe chlorine before its full biocidal function may be achieved. Otherbiocides are attended by odor problems and hazards in respect tostorage, use or handling which limit their utility. To date, no onecompound or type of compound has achieved a clearly establishedpredominance in respect to the applications discussed. Likewise,lagoons, ponds, lakes and even pools, either used for pleasure purposesor used for industrial purposes for the disposal and storage ofindustrial wastes, become, during the warm weather, besieged by slimedue to microorganism growth and reproduction. In the case of therecreational areas, the problem of infection, etc. is obvious. In thecase of industrial storage or disposal of industrial materials, themicroorganisms cause additional problems which must be eliminated priorto the materials use or the waste is treated for disposal.

Naturally, economy is a major consideration in respect to all of thesebiocides. Such economic considerations attach to both the cost of thebiocide and the expense of its application. The cost-performance indexof any biocide is derived from the basic cost of the material, itseffectiveness per unit of weight, the duration of its biocidal orbiostatic effect in the system treated, and the ease and frequency ofits addition ot the system treated. To date, none of the commerciallyavailable biocides have exhibited a prolonged biocidal effect. Instead,their efiectiveness is rapidly reduced as the result of exposure tophysical con ditions such as temperature, association with ingredientscontained by the system toward which they exhibit an aflinity orsubstantivity, etc., with a resultant restriction or elimination oftheir biocidal effectiveness. As a consequence, the use of such biocidesinvolve their continuous or frequent addition to systems to be treatedand their addition to a plurality of points or zones in the systems tobe treated. Accordingly, the cost of the biocide and the labor cost ofsuch means of applying it are considerable. In other instances, thedifiiculty of access to the zone in which slime formation is experiencedprecludes the eifective use of a biocide. For example, in a particularsystem there is no access to an area at which slime formation occurs andit may only be applied at a point which is upstream in the flow system.However, the physical or chemical conditions, e.g. chemical reactivity,thermal degradation, etc., which exist between the point at which thebiocide may be added to the system and the point at which its biocidaleffect is desired render the effective use of a biocide impossible.

Similarly, in a system experiencing relatively slow flow, such as apaper mill, if a biocide is added at the beginning of the system, itsbiocidal effect may be completely dissipated before it has recalled allof the points at which this effect is desired or required. As aconsequence, the biocide must be added at a plurality of points, andeven. then a graduated biocidal eifect will be experienced between onepoint of addition to the system and the next point downstream at whichthe biocides may be added. In addition to the increased cost ofutilizing and maintaining plural feed points, gross ineconomies inrespect to the cost of the biocide are experienced. Specifically, ateach point of addition, an excess of the biocide is added to the systemin order to compensate for that portion of the biocide which will beexpended in reacting with other constituents present in the system orexperience physical changes which impair is biocidal activity.

It is an object of the present invention to provide methods andcompositions for controlling slime-forming microorganisms in aqueoussystems such as cooling water systems and pulp and paper mill systems,and for controlling slime formation or microorganism populations inaqueous bodies in general. Moreover, another object of the invention isthe provision of methods and compositions for controlling slime-formingmicroorganisms in any aqueous system which is conductive to the growthand reproduction of microorganisms and, in particular, cooling water andpaper and pulp mill systems which employ a combination ofbromonitrostyrene and a quarternary ammonium cationic detergent as theslime control agent.

In the practice of the invention, the combination is added to theparticular system being treated; for example, cooling water systems,paper and pulp mill systems, pools, ponds, lagoons, lakes, etc. in aquantity adequate to control the slime-forming microorganisms which arecontained by, or which may become entrained in, the system which istreated. It has been found that such compositions and methods controlthe growth and occurrence of such microorganisms as may populate theseparticular systems. As pointed out in copending application Ser. No.699,355, filed J an. 22, 1968, now abandoned, bromonitrostyrene itselfexhibits a biocidal activity which increases with time during itspresence in the system which is treated. Accordingly, the presentinvention seeks to make use of this feature of the compound togetherwith its biocidal activity, further enhanced by the inclusion of thequarternary compound.

Bromonitrostyrene or, more specifically, betabromobetanitrostyrene (thecis, trans or mixed forms) possesses the generic formula C H CH=CBrNOand the structural formula The quaternary ammonium cationic detergentsare known compounds. The particular detergents as used in accordancewith the present invention are quarternary ammonium compounds such asN-alkyl dimethyl benzyl ammonium chloride with alkyl chain lengths of Cto C or mixtures such as methyl dodecyl benzyl trimethyl ammoniumchloride (80%) and methyl dodecylxylene bis (trimethyl ammoniumchloride). The particular detergents are mentioned in US. Pat.3,231,509. Particular N-long chain alkyl dimethyl benzyl ammoniumchloride compounds which are available as Hyamine 3500 and ETC-927(Onyx) are actually a mixture of compounds wherein the individualcompounds contain difierent length alkyl groups. Hyamine 3500 iscomposed on a weight basis of about 40% C alkyl, 50% C alkyl and C alkyldimethyl benzyl ammonium chlorides while ETC-927 is composed on a weightbasis of about 50% C alkyl, 30% C alkyl, 17% C alkyl and 3% C alkyl.

As earlier stated, the inventive compositions comprise a combination ofthe betabromo-betanitrostyrene and the particular quarternary compoundswith either compound being present in such a quantity as to impart asynergistic behavior to the composition as a whole. The compositionswill generally contain a percentage by weight ranging from about 5% toabout 95% of the styrene compound and from about 95 to about 5% of thequarternary ammonium detergent; and, preferably, from about 95 to 15% ofthe styrene compound and from about 5% to about 85 of said detergent.When these two ingredients are mixed, the resulting mixtures possess ahigh degree of slimicidal activity which could not have been predictedbeforehand from the known activity of the individual ingredientscomprising the mixture. Accordingly, it is therefore possible to producea more effective slime-control agent than has previously been available.Because of the enhanced activity of the mixture, the total quantity ofbiocide required for an effective treatment may be reduced. In addition,the high degree of biocidal effectiveness which is provided by each ofthe ingredients may be exploited without use of the higherconcentrations of each.

To demonstrate the synergism which is provided by the inventivecombinations of compounds, the data as set forth in the Tables wasdeveloped. For the purpose of this study, the N-long chain alkyl (C -Cdimethyl benzyl ammonium chlorides were used as exemplary of thequaternary ammonium chloride detergents. The quaternary ammoniumcompounds for the evaluation consisted in the first class of a mixturerepresenting a range of N- alkyl chain lengths where the alkyl chainlengths were 40% by weight C alkyl, 50% by Weight C alkyl and 10% byweight C alkyl. The compound in the second case was a mixture of N-alkyldimethyl benzyl ammonium chlorides having an alkyl distribution of 50% Calkyl, 30% C alkyl, 17% C alkyl and 3% C alkyl. The com-positions testedthen were the betabromo-betanitrostyrene in combination with thedescribed ammonium chloride compounds.

EXAMPLE 1 Synergism was demonstrated by adding Compound A and Compound Bin varying ratios and over a range of concentrations to liquid nitrientagar medium (Tryptone Glucose Extract Agar) at approximately 50 C. Afterthe medium had solidified in Petri plates, it Was inoculated with abacterial suspension. Following two days incubation, the lowestconcentration of each ratio which prevented growth on the agar mediumwas taken as the end point. End points for the various mixtures werethen compared with end points for the pure active ingredients workingalone in concomitantly prepared agar medium plates. Synergism wasdetermined by the method described by Kull ea al. [F. C. Kull, P. C.Eisman, H. D. Sylwestrowicz and R. L. Mayer, Applied Microbiology, 9,538-41 (1946)] and the relationships,

g +g 1 is synergism, 1 is antagonism and =1 is additivity where,

Q,,=Quantity of Compound A,

an end point Q =Quantity of Compound B,

an end point Q =Quantity of Compound A,

ing an end point Q =Quantity of Compound B,

ing an end point.

acting alone, producing acting alone, producing in the mixture, producinthe mixture, produc- For mixtures of Compounds A and B, and for CompoundA and Compound B acting alone, the following results were observed.

TABLE 1A [Test organism: Aerobacter aeroaenes] Quantities producing andpoints (p.p.m.) Weight ratio Q /Q. of A to B QA QB Mixture QA/Qn QB/QbQB/Qb TABLE 13 [Test organism: Bacillus mycoides] Quantities producingand points (p.p.m Weight ratio QA/Qal 01 A to B QA Qn Mixture QA/QaQn/Qs QB/Qb 0. 25 s. b" 0. 79 iibi his?) 2. 0 4. 0 0. 33 0. 10 0. 43 11.4 12.0 0. 10 0 57 0.67

TABLE 10 [Test organism: Penicillium expanse m] Quantities producing endpoint (p.p.m.) Weight ratio QA/Qn'i' of A to B QA Qa Mixture QA/Qe Q /QbQB/Qb Synergistic combination:

Compound A: Betabromo-betanitrostyrene Compound B: N-alkyl (C 50%, C-30%, C

17%, C 3%) dimethyl benzyl ammonium chloride TABLE 1D [Test organismAerobacter aerogenes] Quantities producing Weight end points (p.p.m.)ratio of QA/Q nl" A to B QA QB Mixture QA/Qn Qn/Qb QB/Qb It will beevident from the data recorded above that compostions of the presentinvention function to control slime growth due to microorganisms notonly at equal portions of the respective ingredients but also where justminor amounts of one or the other are present. This finding of synergismat the lower levels is extremely valuable since it illustratesconclusively that the ingredients are synergistically compatible.

The mode of establishing the synergistic behavior of the compositions ofthe present invention is a widely used and an industrially acceptableprocedure. Although it is believed that the above is sufficient inexplaining the procedure, for a further description thereof referencecan be made to US. Pat. 3,231,509 and its file history where data ofthis nature was considered to be acceptable. Moreover, the article byKull et al. published in Applied Microbiology, 9, 538541, will furnishadditional information in this regard.

For the testing to ascertain synergistic behavior, Aerobacrer aerogeneswas favored since this microorganism is found to exist and found to bemost troublesome in pulp and paper producing processes, as well as incooling towers. Moreover, this microorganism is difiicult to controland/or kill and accordingly its existence does give rise to troublesomeslime. In view of the foregoing, it can then be appreciated that sinceAerobacter aerogenes is prevalent in most slime-affected systems andsince this microorganism is difiicult to control or kill, that oncecontrol of this microorganism is maintained, then for all practicalpurposes the total microorganism population with its different types isconsidered controlled.

When the inventive compositions are employed in the treatment of coolingor paper mill water, they are preferably utilized in the form ofrelatively dilute solutions or dispersions. For example, a preferredsolution comprises between 5% to 65% by weight of the synergisticcomposition in admixture with various solvents and solubilizing agents.An example of such a synergistic composition comprises 10% by weight ofthe mixture of bromonitrostyrene, 10% by weight of the quaternaryammonium compound and the remainder composed of such materials assurfactants, organic solvents and/or water.

Surfactants such as the alkylaryl polyether alcohols,

polyether alcohols, alkyl bezene sulfonates and sulfates.

and the like, may also be employed to enhance the dispersibility andstability of these formulations. The foregoing solutions of the biocidalcompositions are utilized in order to insure the rapid and uniformdispersibility of the biocides within the industrial water which istreated. It has been found that either aqueous or non-aqueous solventsare generally suitable in the preparation of compositions of theinvention. For example, organic solvents such as methyl Cellosolve andaliphatic and aromatic hydrocarbons, e.g. kerosene, can be used quitesuccessfully. Based upon the synergism study as outlined above, it wasascertained that in the treatment of papermill and cooling water,effective biocidal action is obtained when the concentration ortreatment level of the combination or admixture of biocides is between0.5 parts per million to 1000 parts per million, and preferably between1 and parts per million, based upon the total content of the systemtreated, such as the total quantity of cooling water or paper millwater. The compositions may also be utilized for the preservation ofslurries and emulsions containing carbohydrates, proteins, fats, oils,etc. Dosage levels for this purpose range in the vicinity of 0.5%. Thecompositions of the invention which can be prepared by merely combiningthe respective ingredients and mixing thoroughly at standard conditionsmay be fed continuously to the treated system, e.g. by means of ametered pump, or may be fed periodically at intervals calculated tocontrol the growth of slime-forming organisms in the system. Naturally,in the treatment of cooling water the feeding of the inventivecompositions must be designed to compensate for blow-down in thosesystems which employ that expedient.

Although the styrene compound has been limited in this description to aspecific styrene, it is obvious that slight modifications of thiscompound would also operate in the same manner. Likewise, while thequaternary ammonium chloride detergent has been specificallyexemplified, it is obvious that enhancement would also exist if thealkyl substituents were altered percentagewise. These modificationswould be obvious to the worker once appraised of the invention.Accordingly, modifications of this nature are included within thegeneral scope of the invention.

As would be expected, the inventive composition may be added to thecooling water or paper and pulp mill systems ant any convenient point.Naturally, in oncethrough or non-circulating systems, the compositionmust be added upstream from the point or points at which microorganismcontrol is desired. In circulating systems or pulp and paper systems,the compositions may be added at any point provided that the time lapseand the conditions experienced between point of addition and the pointat which the effect of the composition is experienced are not so drasticas to result in the neutralization of the effect of the composition.

In order to establish the effectiveness of the synergistic combinationin combating or controlling slime formation which was being experiencedin various paper and pulp mills, the combination was tested with watersamples derived from actual mills. More specifically, actual watersamples were taken from pulp and paper mills which were experiencingslime problems due to the micoorganism population of the water.

As is well-known, slime problems are generally caused by a combinationof microorganisms which although primarily bacteria and fungus, in somecases also includes algae. The samples taken were subjected to arespirometer evaluation which in effect established the property of thesynergistic combination at specific treatment levels to inhibit thegrowth of the microorganisms of the sample.

Respirometer techniques are widely used to evaluate the biocidalactivity of various materials. The techniques and the instrumentsthemselves are described in Manometric Techniques, Umbreit et al., 4thedition, 1964, Burgess Publishing Company, Minneapolis, Minn.

Generally, the procedure used entails adding a sample of the Water whichwas taken from the operating mill to a manometer flask, together withdilutions of the synergistic combination. The samples of water whichwere used to evaluate the present combinations were taken from the whitewater of various pulp and paper mills. The manometer flask is equippedwith a center well into which is placed a known volume and concentrationof potassium hydroxide. The potassium hydroxide possesses the propertyof absorbing carbon dioxide. The flasks bearing the respective solutionsare attached to the manometer and incubated with shaking in a constanttemperature bath. The microbial population in the water sample in normalrespiration will consume a certain amount of oxygen from the closed gasphase between the surface of the Water sample and the manometer fluid.Concurrent with the consumption of oxygen is the evolution of carbondioxide which is absorbed by the potassium hydroxide contained by thecenter well which, in turn, changes the manometer setting. The changesin manometer settings are related to the utilization of oxygen by themicrobial population in the sample. Inhibition of the respiration of themicrobial population by the added synergistic combination is determinedby comparing manometer readings with readings obtained from samplestreated accordingly which contain no synergistic combination.

The procedure not only indicates the effectiveness or theineffectiveness, as the case might be, of the combination to control therespiration of slime-forming microorganisms at various treatment levels,but also indicates the effectiveness of the composition in controllingthe growth of these microorganisms. In addition, the procedure permitscorrelation of its efiicacy with field conditions since actual whitewater samples from mills experiencing slime problems are employed.Accordingly, the intended purpose of the product, i.e. the control ofslimeforming organisms found in commercial systems, is directlyevaluated.

Specific Embodiments The synergistic composition can be produced bysimply mixing the respective ingredients thoroughly. Accordingly, thecomposition of Example 2 was obtained by mixing a composition comprisingthe listed components in the specified percentage by weight.

8 EXAMPLE 2 Percent N-alkyl (C -40%, C 50%, C 10%) dimethyl benzylammonium chloride 8 Betabromo-betanitrostyrene 1O Methyl Cellosolve l0Non-ionic surfactant (isooctylphenyl-polyethoxy ethanol, e.g. TritonX-114) 5 Aromatic hydrocarbon) Amsco-F) 67 The composition obtained inaccordance with Example 2 was evaluated utilizing the above-describedrespirometer method. The percentage inhibition at the particulartreatment levels are recorded in the following Table 2 for each of thecompositions. The Table, in addition, sets forth the fact that the whiteWater samples tested were derived from different pulp and paper mills.These mills are identified respectively as Mills A and B. In addition,the present composition was compared with a commercially availablebiocide which has found extensive use in the paper and pulp industry.This biocide contains 20% by weight bis (trichloromethyl) sulfone and 5%by weight methylene bisthiocyanate.

TABLE 2 Percentage inhibition Parts per million 1.25 2.5 5.0 12.5 25 50White water sample derived from Mill A Composition of:

Example 2 22 45 78 99+ 99+ 99+ Commercial biocide 21 28 55 65 68 71White water sampig derived from Mill Example 2 Commercial biocideEXAMPLE 3 The composition of this Example was obtained by mixing theingredients listed following in the specified percentage by weight:

Percent N-alkyl (C 50%, C -30%, C -17%, C

3%) dimethyl benzyl ammonium chloride 5 Betabromo-betanitrostyrene 5Dimethylformamide Slime Control Effectiveness The inventive methods andmaterials were also tested with respect to their performance in thecontrol of slime formation in industrial systems. In this test anindustrial recirculating water was obtained from a system which wascurrently experiencing problems in respect to the formation of slime bymicroorganisms. Such tests do not demonstrate the efiiciency of thebiocide employed with respect to specific species of microorganisms butinstead supply a practical demonstration of the efficacy of the biocidetested in relation to those communities of microorganisms which haveevidenced their ability to form slime in actual industrial systems.

In the testing of recirculating water samples, a substrate evaluationwas employed. In such testing, identical portions of water samples aretreated with varying concentrations of biocide and two portions are leftuntreated to serve as controls. The control portions are plated fortotal count at the beginning of biocide treatment and all portions areplated for total count at some suitable time period(s) after beginningbiocide treatment. Using the counts obtained from the platings, thepercentage kill (based on the initial control count) may be calculated.In the following example, the water sample was taken from a papermachine tray water sample from a paper mill located in the northeasternUnited States.

For the purposes of comparison, the composition of Example 3 wasevaluated with two recognized commercial biocides.

In order to ascertain whether in fact the inventive com positions wereeffective in controlling fungi, evaluations were made following theprocedure described by Shema et al., Journal for the TechnicalAssociation of the Pulp and Paper Industry, 36, 2OA-3OA, 1953. Thedescribed procedure generally entails incorporating the biocide undertest in a nutrient substrate such as agar, malt, etc. and pouring theresulting medium in a Petri dish and allowing the medium to solidify. Abutton of fungus inoculum is placed on the surface of the solidifiedmedium and the medium is incubated for a period of 14 days. After theperiod, the diameter of the colony is measured and compared with thediameter of the button of inoculum originally placed upon the surface.If there is no increase in the diameter, the growth of the fungus isconsidered to be completely inhibited and the treatment level whichelfectuates this is considered the inhibitory concentration.

The fungi species utilized as the test microorganism to evaluate theefficacy of the present compositions were Penicillium expansum andAspergillus niger. The study revealed that the composition of Example 2inhibited the growth of Penicillium expansum at a treatment level of 25p.p.m., while 125 ppm. completely inhibited the growth of Aspergillusniger. The composition of Example 3 inhibited the growth of Penicilliumexpansum at a level of 100 p.p.m. and successfully inhibited the growthof Aspergillus niger at a treatment level of 300 p.p.m.

Accordingly, since the waters of pulp and paper mills and the water ofcooling water systems generally predominately contain bacteria such asAerobacter aerogenes and some fungi such as Penicillium expansum andAspergillus niger, it is apparent from the foregoing evaluations andstudies that the inventive composition will elfectuate the claimedobjective of controlling microorganisms of aqueous systems.

It should be noted that while the preponderance of evidence has beenderived from the treatment of samples from paper and pulp mill aqueoussystems, the compositions and methods of the present invention arebroadly applicable to the treatment of aesthetic waters as Well asindustrial waters such as cooling waters which are plagued by depositsformed by slime-forming organisms, or by the very presence of suchorganisms.

Having thus described the invention, what is claimed is:

1. A composition for the control of slime in aqueous systems comprisingbetabromo-betanitrostyrene and a mixture of N-alkyl dimethyl benzylammonium chloride compounds wherein the alkyl distribution is 40% C 50%C and 10% C wherein the weight ratio of the styrene to the chloridemixture is from about 95% to 5% to about 5% to 95 2. The composition ofclaim 1 wherein said weight ratio is 50% to 50%.

3. A composition for the control of the growth of the microorganismAerobacter aerogenes in aqueous systems in which said microorganism isfound, comprising, betabromo-betanitrostyrene and a mixture of N-alkyldimethyl benzyl ammonium chloride compounds, wherein the alkyldistribution is 50% C 30% C 17% C and 3% C and wherein the weight ratioof the styrene to the chloride mixture is from about 95 to 5% to about15% to 4. The composition of claim 3 wherein said weight ratio is 50% to50%.

5. A method for the control of slime in aqueous systems which comprisesadding to said system from about 0.5 to about 1000 parts by weight permillion parts by weight of said system of a synergistic compositioncomprising betabromo-betanitrostyrene and a mixture of N- alkyl dimethylbenzyl ammonium chloride compounds wherein the alkyl distribution is 40%C 2, 50% C and 10% C wherein the weight ratio of the styrene to thechloride mixture is from about to 5% to about 5% to 95 6. The method ofclaim 5 wherein said aqueous system is a cooling water system.

7. The method of claim 5 wherein said aqueous system is a pulp millsystem.

8. The method of claim 5 wherein said aqueous system is a paper millsystem.

9. A method for controlling the microorganism Aerobacter aerogenes in anaqueous system in which said microorganism is found which comprisescontacting said microorganism in said system with 0.5 to 1000 parts byweight per million parts by weight of said system of a compositioncomprised of betabromo-betanitrostyrene and a mixture of N-alkyl benzylammonium chloride compounds, wherein the alkyl distribution is 50% C 30%C 17% C and 3% C and wherein the weight ratio of the styrene to thechloride mixture is from about 95% to 5% to about 15% to 85%.

10. The method of claim 9 wherein said aqueous system is a cooling watersystem.

11. The method of claim 9 wherein said aqueous system is a pulp millsystem.

12. The method of claim 9 wherein said aqueous system is a paper millsystem.

References Cited UNITED STATES PATENTS 2,335,384 11/ 1943 Bosquet et al424349 3,231,509 1/1966 Shema 424-300 3,300,373 1/1967 Wolfson 16Zl903,342,671 9/ 1967 Sousa et a1 424-349 OTHER REFERENCES ChemicalAbstracts, vol. 70, 67l63w, 1969.

ALBERT T. MEYERS, Primary Examiner L. SCHENKMAN, Assistant Examiner US.Cl. X.R.

